Such component assemblies are extremely well known from many patent specifications, with the nut element normally having a flange region which is arranged at the side of the sheet metal part remote from the head part of the bolt. The bolt element is then normally used in order to secure another component to the component assembly consisting of the nut element and the sheet metal part. The other component is clamped between the head part of the bolt element and the sheet metal part.
Arrangements of this kind are also known in which one operates without a further component, for example when the nut element is used as a drain point at an oil pan or sump. In this case the shaft part from the bolt element is screwed into the thread of the nut element and seals directly or indirectly by means of an interposed seal against the underside of the nut element.
A problem with such oil pans is that the oil pan cannot be completely emptied on draining the oil because the flange region of the nut element has a certain constructional height within the oil pan and thus a residual volume of oil cannot be drained off.
This residual volume is however problematic, in particular but not exclusively when the engine of the car is started as a test or for running in before leaving the manufacturer's plant. It is namely usual nowadays to allow the engine to run for about 15 minutes at the manufacturer's plant and to subsequently carry out an oil change. It is particular important with this first oil change to remove swarf and abrasive particles which are unavoidably present in the engine with the oil, particularly since the first regular oil change will only be carried out after 10,000 to 20,000 km. The larger the residual volume of oil which cannot be drained the more swarf and abrasive particles remain in the engine and the higher is the probability that motor damage will be caused hereby.